1. Field of the Invention
The present invention relates to an electronic apparatus such as a portable radio device, and more particularly to an electronic apparatus which appropriately controls the current supplied by a current supply unit in accordance with the operational modes of the apparatus.
2. Description of the Related Art
A portable electronic apparatus such as a portable radio device is mounted with a rechargeable battery to be used as a power source when the apparatus is in portable use. To charge the battery, a charger is connected to the portable apparatus.
In the portable electronic apparatus of this type, such as a portable radio device, the operating current varies according to the operational modes, that is, whether a radio unit in the portable radio device is in a transmission mode or a standby mode. The charging current supplied by the charger, however, is kept constant irrespective of the operational modes of the portable radio device.
Therefore, when the portable radio device is operated while it is connected to the charger, the current flowing through the rechargeable battery varies as the operational mode of the radio device changes, whereby the rechargeable battery is likely to be deteriorated. If, for example, the operating current in an operational mode is less than a predetermined operating current for operating the radio device, the current flowing through the rechargeable battery increases so as to exceed the battery's allowable current values (specified charging current), to thereby deteriorate the battery.
On the other hand, there is an event in which the supply of the operating current to the portable radio device is insufficient in a certain operational mode of the radio device. In such event, an appropriate operation of the radio unit cannot be ensured. This takes place when the operating current in the certain operational mode is larger than the predetermined operating current of the radio device so that the radio device cannot operate appropriately.
The above discussion also applies to other electronic apparatuses having a plurality of operational modes which require different operating currents.
Conventionally, electronic apparatuses of the abovedescribed type have a trouble in operating the apparatus when the apparatuses are connected to the charger.